Rosin-soap sizing composition.



.TUDSON A. DE CEW, 0F MONTREAL, QUEBEC, CANADA.

ROSIN-SOAP SIZING COMPOSITION.

No Drawing.

Specification of Letters Patent.

To all whom it may concern Be it known that I, J UDSON A. DE Cnw, of the city of Montreal, in the Province of Quebec and Dominion of Canada, have invented new and useful Improvements in Rosin-Soap Sizing Compositions, of which the following is a full, clear, and exact de scription.

This invention relates to a sizing composition, which is particularly adapted for use in the manufacture of paper. Rosin soap used in the sizingof paper is a well-known product, and is usually made-by saponifv ing rosin by boiling it with a solution of caustic soda or sodium carbonate. To completely saponify 100 lbs. of rosin, 16 lbs. of sodium carbonate is required in which case the product is a soap consisting of sodium resinate only. It is possible in making this rosin size to use less than 16 lbs. of sodium carbonate, in which case a portion of the rosin remains unsaponified but emulsified in the soap. The solvent power of this soap for the rosin depends upon the concentration of the soap. For example, when the soap is boiled to such concentration that it contains about 30% of water, one pound of rosin soap will hold in emulsion from one to two pounds of rosin. The rosin emulsified in the rosin soap is described as free rosin. If this rosin soap is diluted, its capacity to hold the rosin in solution is diminished so that if it were diluted, for instance, to parts of water to one part of soap, it could not hold more than about 20 lbs. of rosin to 80 lbs. ofsoap, when it is emulsified in the ordinary manner. Any excess of free rosin over this amount would separate from the emulsion in coarse lumps or particles, and not in the form of an emulsion. It is found, therefore, by emulsifying rosin soap in hot water to containing over 20% freerosin, that the free IS in very coarse parrosin in this emulsion ticles.

' I have discovered that by. adding to the composition of the rosin soap such a mate- 'rial as tannic acid, the rosin in the emulform an emulsion sion formed, on dilution, will separate into very minute particles as shown by microscopic examination. I'have also found that when this tannin product' is incorporated into the composition of rosin size, a much higher proportion of free rosin can be brought by dilution into an emulsion, the particles being too fine to separate out. As the efliciency of a rosin soap for sizing paper depends upon thefineness of the free rosin particles in the emulsion and the amount of this free rosin available, I am enabled in this way to produce much more efficient sizing material than the ordinary resinate of soda. The presence of the tannin compounds in the rosin soap greatly increases the solvent power of the soap for the free rosin, so that it is more diflicult to throw this from solution by the addition of water. There is a certain chemical ailinity which is difficult to explain, but the presence of these tannins gives to the unsaponified rosin a more soluble character. It is on this account that a perfect emulsion containing a high percentage of free rosin can be formed by this process.

In carrying out myprocess, I boil 100 lbs. of rosin with from 8 to 10 lbs. of sodium carbonate,-and approximately 20 to 30 lbs. of water, adding during the process of boiling about one pound of the tannin product, such as tannic acid, or any commercial tannin extract. The boiling is contnued until the soda has saponified all the rosin which it is capable of, or until the soda has all been taken up leavingabout30 to 50% of the rosin still uncooked and unsaponified. The remainder of the rosin is unsaponified, but is in complete emulsion in the soap. By adding sufiicient water to this solution, the uncooked rosin is set free in the form of a very fine emulsion, which is it very desired product forsizing mater1a Having thus described my invention, what I claim is:

1. A method of making sizing material which consists in cooking rosin with less Patented June 9, 1914. Application filed June 13, 1912. Serial No. 703,496.

than 16% by weight of sodium carbonate, complete saponification, and adding thereto and adding thereto a tannin. a tannin product.

2. A rosin size emulsion, comprising a In witness whereof I have hereunto set rosin so p containing free rosin and a tanmy hand in the presence of twowitnesses.

5 nin pro uct. JUDSON A. DE CEW.

3. A method of making sizing material, Witnesses:

which consists in boiling rosin with an STUART R. W. ALLEN, amount of alkali less than is required for G. M. MOBELAN-D. w 

